Radio access networks (RAN) are networks for providing communication between cell sites, which provide cellular communication with handsets, and a network backbone or backhaul that connects the cell sites to other cell sites or phone systems. A RAN is typically considered to consist of two distinct topological parts. A LowRAN, or access RAN, is a portion of the network that is comprised of a point-to-point topology between the cell site and an aggregation point. A HiRAN consists of a high capacity and highly redundant aggregation network composed of a plurality of aggregation nodes. These aggregation nodes connect the cell sites to the backhaul or backbone network.
Many RAN operators design backhaul networks based on Ethernet as a transport and aggregation layer. Newer RANs include HiRANs that are based on a metro Ethernet network architecture. This metro Ethernet network architecture is based on provider bridging architecture, virtual private line services (VPLS), provider backbone bridges (PBB)/provider backbone transport (PBT) or a combination of these technologies. Operators also design these architectures with Connectivity Fault Management (CFM) (IEEE 802.1ag) as a basic requirement for OAM. The nodes in the aggregation network thus implement CFM.
A LowRAN does not support CFM. Rather, the LowRAN supports Ethernet in the first mile (EFM) (IEEE 802.3ah). CFM is not suited for use in the LowRAN, because it is a complex resource-intensive protocol. Equipment in the LowRAN do not typically have sufficient hardware and software capability to support CFM. Upgrading or providing sufficient resources in the equipment in the cell sites in LowRAN is expensive. As a result, the RAN operators can only take advantage of the CFM-OAM functionality up to the LowRAN, that is, within the HiRAN. This makes it more difficult to debug issues related to connectivity or quality degradation in the LowRAN, requiring an onsite visit to the cell site in many cases.